Since
the 80’s, the monitoring of silicic volcanoes using geophysical techniques has
largely been developed around the world. This has allowed important advances on
our understanding of magmatic and volcanic processes.
First, the
concept of magma chamber has radically changed. Indeed, geophysical surveys do
not find large liquid magma bodies below active volcanoes, but only large,
diffuse, partial melt zones. Magma chambers are now described as large mush
zones located at different levels in the crust and constructed by accumulation
of small magma batches over hundreds of millions of years. The two-phase
dynamics of a crystal and magma mixture thus controls melt extraction during
periods of unrest.
Second, the
activity of silicic volcanoes has appeared cyclic and marked by different
periods of cyclicity going from tens of years to the second. Some of them are
clearly linked to the very different physical properties and behaviors of the
different phases present in magmatic systems: crystal, melt and gas.
In the end, at arc-volcanoes,
melts extracted from the mantle face a complex and vertically stratified
filter: the crust. Understanding the dynamics of a three-phase mixture in a
vertically stratified environment is thus crucial for the assessment of
eruptive risk, in particular to describe the transfer function characteristic
of this crustal filter.

The video for this talk should appear here if JavaScript is enabled.If it doesn't, something may have gone wrong with our embedded player.We'll get it fixed as soon as possible.